/**
 * base64ToFile
 */
export function base64ToFile(dataurl, filename) {
  var arr = dataurl.split(","),
    mime = arr?.[0]?.match(/:(.*?);/)?.[1],
    bstr = atob(arr[1]),
    n = bstr.length,
    u8arr = new Uint8Array(n)
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n)
  }
  return new File([u8arr], filename, { type: mime })
}

/**
 * file to base64
 * 单一原则 
 */
export function fileToBase64(file) {
  return new Promise((resolve, reject) => {
    // file to base64
    var reader = new FileReader();
    // 当文件处理完成的回调函数
    reader.onload = function (e) {
      resolve(e.target.result)
    };
    // 文件处理 file=>base64
    reader.readAsDataURL(file);
  })
  
}